Acoustics of Aircraft Engine-Duct Systems

The acoustic and instability waves of jets confined inside an acoustically lined rectangular duct

“…The above two equations are the same as those obtained in the literature for uniform mean flows (Nayfeh et al [3]). …”

“…At the acoustically treated top and bottom walls, located at y = ±h, the kinematic boundary condition is the continuity of particle displacement at the lined walls. For harmonic waves, it yields (Nayfeh et al [3] …”

“…A point-reacting wall impedance model will be used in the present study [3]. In this model, the impedance of the wall is given by…”

“…Duct acoustics and wave attenuation by wall liners have been investigated extensively in the literature (see excellent reviews by Nayfeh, Kaiser and Telionis [3], Eversman [4] and references cited therein). Pridmore-Brown [5] first formulated the acoustic wave propagation problem in an attenuating duct with non-uniform mean flows.…”

On Some Fundamental Flaws in Present Aeroacoustic Theory

“…Thus, any practical experience in the accurate analysis of this kind would be of much value. However, appraising the current state of this research direction, now one has to repeat the phrase from section II of reference [77]: &&No solution to these equations subject to general initial and boundary conditions has been found for general mean #ows''.…”